More anytotx Headers and Formats

The anytotx program may print additional headers - X-Anytotx-Content-Type-Initial and X-Anytotx-Identified-By-Initial - in Texis version 6. These have the same meaning as their non--Initial counterparts, but the -Initial versions have a lower precedence. E.g. an X-Anytotx-Content-Type header overrides X-Anytotx-Content-Type-Initial if both are present.

anytotx also supports Open Document Format files in version 6.